46. Physicists Create a Way to Hide in Time

Cloaking method can occlude entire events.

Recently physicists have created prototype invisibility cloaks that conceal objects from light, sound, and water. Last January, Cornell physicist Alexander Gaeta one-upped them all by building a cloak that hides entire events.

Gaeta exploited the fact that we perceive objects only because they scatter light. He started by splitting a light beam as it passed through a 400-foot-long glass fiber, which created a 40-picosecond gap of darkness as one part of the beam lagged behind the other. During that brief time, he shot a laser through the unlit gap. Finally Gaeta rejoined the light fragments to preserve the original beam. An observer at the end of the fiber would never know the laser had been fired, because it never interacted with the light beam. Gaeta suggests this approach may have applications in data transmission. Alas, sneaking out of work undetected is well beyond current technology.